2006 Volume 49 Issue 3 Pages 397-402
In this study, diffusion creep in Sn-37Pb as a low melting point alloy during a nanoindentation creep test was examined. The creep exponent, n, from the relationship between hardness and indenter dwell time decreases as a function of time and is saturated when n=1. From observations of the indented surface, plastic deformation due to the indenter takes place in the early stages. On the other hand, granular deformation takes place in the middle and last stages. Finite element analysis revealed that the reduction in Mises stress is faster than that of hydrostatic stress. Multiaxial stresses appear below the indenter, and axial components of stress remain after relaxation. Since the core hydrostatic stress causes a gradient in the chemical potential at grain boundaries, diffusion creep affects the behavior of indentation creep in the last stage. A transition from power-law creep to diffusion creep occurs below the indenter.